1. Field of the Invention
The present invention relates to a thin type micro reformer used in a fuel cell, and more particularly, to an improved thin type micro reformer having a fuel charger disposed between a reformer portion that reacts by absorbing heat and a CO remover that reacts by emitting heat, in order to partition the reformer portion and the CO remover. The reformer allows effective reforming response on a single sheet of substrate, an inner pressure inside the CO remover to decrease, and outside air to enter by means of a small pump.
2. Description of the Related Art
A recent increase in the use of mobile phones, PDAs, digital cameras, laptop computers, and other small, portable electronic devices—and especially, the beginning of DMB broadcasting for mobile phones—has given rise to a need for more effective power supplies for portable, compact terminals. Lithium ion rechargeable batteries used widely today provide power for only 2 hours of DMB viewing. While efforts are underway to enhance their performance, the fuel cell is viewed as an alternate solution to the above problem.
Methods of such fuel cells include direct methanol type fuel cells that supply methanol to fuel electrodes and reformed hydrogen fuel cells (RHFC) that extract hydrogen from methanol to supply to fuel electrodes. RHFC fuel cells use hydrogen as fuel, as in a polymer electrode membrane (PEM), and have the benefits of high output, power capacity available by volume unit, and no byproducts other than water. However, a reformer needs to be added to the system, making the device unsuitable for miniaturization.
To derive a high power output from such a fuel cell, a reformer is used to convert liquid fuel to hydrogen gas fuel. This type of reformer includes an evaporator for converting liquid methanol to a gaseous form, a reformer portion that converts methanol fuel to hydrogen through catalytic conversion at a temperature between 250° C. and 290° C., and a CO remover (or a PROX) that removes the byproduct carbon monoxide. Technology is needed to maintain the reformer portion (that reacts to absorb heat) at a temperature between 250° C. and 290° C., and the CO remover at a temperature between 170° C. and 200° C., in order to produce optimum reaction efficiency.
However, silicon, that has favorable heat conducting characteristics, is used as a substrate material and must be operated within a region that has been heat insulated to prevent heat leakage to the outside. Thus it is difficult for the temperature on one substrate to be maintained in two other separate regions, and a configuration allowing for this is required.
As shown in FIG. 1, a conventional compact reformer 250 is disclosed in Japanese Patent No. 2004-288573, which is hereby incorporated by reference. This conventional compact reformer 250 includes a heat insulating package 258 and combustion fuel evaporator 251, a generator fuel evaporator 255, a burner 252, a CO remover 257, another burner 254, a reformer portion 256, and yet another burner 253, sequentially stacked within the heat insulating package 258.
Heat insulated supports 261 and 262 are installed below the combustion fuel evaporator 251 to support the combustion fuel evaporator 251. The combustion fuel evaporator 251 is separated from the inner walls of the heat insulating package 258. Accordingly, because this conventional reformer has a multi-layer structure, it is difficult to make compact.
Another conventional compact reformer 350 is shown in FIG. 2 and is disclosed in Japanese Patent No. 2003-45459, which is hereby incorporated by reference. This conventional reformer includes a first substrate 352 forming a flat cover, a second substrate 354 forming passages 354a on one side thereof and having a catalytic layer 354b formed within, and a third substrate 356 having a heat insulating cavity 356b with a mirror surface 356a formed therein. A reformer portion is formed through the passage 354a of the second substrate 354 and has the catalytic layer 354b that produces hydrogen gas and CO2 from methanol and water, and a thin film heater 358 is provided underneath the catalytic layer 354b along the reformer portion.
Although the provision of the heater 358 within the passages of the above conventional reformer raises heat efficiency, the structure is complex and is therefore difficult to make, and the catalytic layer 354b is limited to one portion, reducing reforming efficiency.
A further conventional compact reformer 400 is shown in FIG. 3 and is disclosed in Japanese Patent No. 2004-066008, which is hereby incorporated by reference. This conventional technology provides a highly heat conductive aluminum heat conducting portion 413 (for very efficient heat conducting) between two substrates 411 and 412, and a reactive catalytic layer 416 within the fine passage 414 formed in the inner surface of the main substrate 411.
A combustion catalytic layer 417 is provided in a fine passage 415 formed in the inner surface of the combustion substrate 412, and a thin film heater 423 is provided on the outer surface of the combustion substrate 412.
Combustible fuel supplied within the passage 415 is combusted through the combustion reaction on the combustion catalytic layer 417. The heat energy produced through the combustion and the energy from the heating of the thin film heater 423 combine to heat the inside of the passage 414.
Accordingly, loss of heat energy supplied to the reactive catalytic layer 416 installed inside the passages 414 and 415 of the substrates 411 and 412 is reduced.
However, in the above-described conventional structures, at least 3 thin films are stacked, forming a large reformer. Also, in order to supply air into the CO remover that has a high inner pressure, a large-sized air supplying pump must be used to supply pressurized air. Thus, miniaturization of components required by the reformer is problematic.